I have used trans go shift kits in many of my past vehicles .....89 IROC.....93 astro van.....95 TA and my current 2000 TA

the change in shift quality from the installation of a kit is very noticeable......in high school i put in a BM SK in my 1980 firebird that had a TH350......those tire chirping shifts sure were cool

now that i am older.... shifts that bang into gear and jar my dentures loose (j/k ) are not so much fun

one of my issues with TG kits is the lack of uniformity in shift quality .....1-2 shift bangs into gear ( with or without those stacks of washers in the accumulator )while the others kinda whimper ...........except the TCC lockup that is

i have read in other automotive forums about the sonnax SK and how much better the shift quality was compared to the TG kit.....well that got my curiosity up so i just had to try it !!!

the P/N for the kit is HP-4L60E-01 and comes with many parts that can be bought separately from sonnax......the instructions in the kit are very good .....but for a newbie who has never been in a transmission before i recommend reading many available technical reference materials...... such as those published by ATSG

in addition to the kit i also installed the sonnax forward and reverse abuse valve kit 77754-21 ..........you need 2 of those.........and their heavy duty 2-3 shift valve 77754-41.....and the accumulator valve train kit 77777L-K

when i did my TG kit install i still had worn rubber engine mounts and a stock exhaust ....now i have poly mounts and headers.....the old rubber mounts allowed me to lower the tranny enough to get to the servo and remove it.....no going now with the unforgiving poly mounts.......so the sonnax parts for the servo did not get installed YET....it will have to wait til i drop the engine out later and then i have the heavy duty sonnax 2nd and 4th piston kits to put in the servo

just as the TG kit does you will have to drill holes in the separator plate......if it is a 1st time install for you i recommend you get a NEW separator plate as the steel check ***** will have worn the holes to a much larger size.....new plates can be had either from the dealer or trans go.....side note....i got a new sep plate from the dealer and they NOW come with the gaskets glued ( ? ) to the plate and the filter screens incorporated in the gaskets......the sonnax kit comes with plastic checkballs so you dont have to worry about plate wear again

the sonnax kit comes with their 4L60E-LB2 line booster part and a spacer to retro fit it into a 4L60E-LB1 part for those yrs requiring that part.....under the car fiddling with the booster install ( which is NO fun ) i did not feel like messing with another part to line up during the install process ...........so i went ahead and got a 4L60E-LB1 boost valve

with the sonnax kit installed i can say the shift quality is a 100x better than the TG kit......FIRM shifts in EVERY gear.....that will keep your fillings in place

and now for pics...........

 

truck pan fits nicely under a f bod

 

valve body..........1-2 accumulator already removed

 

stock 1-2 setup

 

sonnax 1-2 setup with the pinless piston

 

stock forward/reverse abuse valve

 

sonnax abuse valve

 

 

new GM plate with screens built in

 

 

sonnax 2-3 shift valve

 

the sonnax 2-3 valve needs more oil.......so you can mod the gasket or drill the VB.........guess which one i did

 

stock TCC valve line up....this valve is the 2001 change GM did to the TCC line up.....but my 2000 has it...........go figure

 

sonnax TCC valve......that spring is STRONG

 

sonnax 3rd accumulator check valve

 

3-4 accumulator pinless piston with spring

 

piston installed ......no spring in yet

 

sonnax line booster .....the middle spring is the reused stocker

 

plastic checkballs installed in VB

 

sonnax servo springs with a vette servo.....not installed